Topological Hall effect in thin films of Mn1.5PtSn

Peter Swekis,Jacob Gayles,Walter Schnelle,Dominik Kriegner,Richard Schlitz,Anastasios Markou,Claudia Felser,Sebastian T. B. Goennenwein

doi:10.1103/physrevmaterials.3.013001

Abstract

Spin chirality in metallic materials with non-coplanar magnetic order can give rise to a Berry phase induced topological Hall effect. Here, we report the observation of a large topological Hall effect in high-quality films of Mn$_{1.5}$PtSn that were grown by means of magnetron sputtering on MgO(001). The topological Hall resistivity is present up to $\mu_{0}H \approx 4~$T below the spin reorientation transition temperature, $T_{s}=185$~K. We find, that the maximum topological Hall resistivity is of comparable magnitude as the anomalous Hall resistivity. Owing to the size, the topological Hall effect is directly evident prior to the customarily performed subtraction of magnetometry data. Further, we underline the robustness of the topological Hall effect in Mn\textsubscript{2-x}PtSn by extracting the effect for multiple stoichiometries (x~=~0.5, 0.25, 0.1) and film thicknesses (t = 104, 52, 35~nm) with maximum topological Hall resistivities between $0.76~\mu\Omega$cm and $1.55~\mu\Omega$cm at 150~K.

Highlights

Topological magnetic structures have become of great interest recently, attributed to the emergent transport phenomena associated with the magnetic texture [1]
The measured Hall resistivity can be separated into the ordinary Hall effect (OHE) [3] dependent on the external field (H ) and the anomalous Hall effect (AHE) which scales with the saturation magnetization (Ms)
The physics regarding the relation of the topological Hall effect (THE) to the AHE have not been completely explored or understood, where in our films we clearly observe a difference in the relation that depends on the spin reorientation transition temperature

Summary

INTRODUCTION

Topological magnetic structures have become of great interest recently, attributed to the emergent transport phenomena associated with the magnetic texture [1]. Recently an additional Hall-type contribution was proposed that scales neither with the magnetization (M) nor with the externally applied field, termed the topological Hall effect (THE) [8,9]. This THE has been proposed to originate from a finite scalar spin chirality [10], skyrmions [8], and Weyl points [11]. As electrons couple to such spin textures, they acquire a finite Berry phase acting as a magnetic field This in turn results in an additional contribution to the Hall effect [19]. We point out the robustness of the THE in Mn2−xPtSn by comparing different compositions and film thicknesses, as well as previously reported results on Mn2PtSn films

EXPERIMENTAL DETAILS

Structural characterization

Magnetometry and magnetotransport properties

CONCLUSION